a. Field of the Invention
This invention relates to a self-inflating air cushion bag. More particularly, it is concerned with a safety air cushion bag or pillow for use in an automobile and like other vehicles, which is inflated by a pressurized gas at the time of collision of the vehicle in traffic accident so as to protect riders or passengers in the vehicle from unexpected danger of the traffic accident.
B. Description of Prior Arts
Owing to remarkable improvement in the running performance of automobiles in conjunction with improved road conditions, the automobiles can be driven as high a speed as ever made possible. With increase in the running speed in such vehicles, however, collision accidents happen not infrequently between automobiles running along the road at such high speed, thereby causing serious injury or tragic death of the vehicle riders or passengers.
In order to avoid such unexpected misery on the part of the vehicle riders, use of a safety seat belt has been prompted, which has now become the essential equipment in most automobiles. However, even the safety seat belt is not still safe enough to protect the vehicle riders from unexpected injury or death due to extremely heavy shock at the collision, particularly, in the case of the automotive vehicles running at a speed as high as 35 miles/hour and above, at which an incredibly heavy shock is potentially applied to the vehicle riders.
Therefore, in addition to the safety seat belt, an air-cushion bag or pillow which is inflated instantaneously at the time of a collision accident being taken place, and which absorbs the great shock imposed on the human body, has been contemplated for use along with the safety seat belt.
For this kind of self-inflating air cushion bag or pillow, there has already been known such one that is provided in one part thereof with the circular air outlet port which serves as an escape from a load imparted to the air cushion bag, after it is inflated, by the weight of the vehicle rider who is leaning frontward due to the moment of inertia at the collision so that he or she may be prevented from bouncing by the restitutive force of the inflated air cushion bag.
In the air cushion bag of the above-described construction, the circular air outlet port is covered with a gas-permeable cloth, the peripheral edge of which is joined to the main body of the air cushion bag by any appropriate expedient such as, for example, stitching, to thereby control the outflowing quantity of air from the inflated air cushion bag in accordance with the load imparted thereto. With this inflated air cushion bag, however, there exists a serious disadvantage such that, since an excessive load is instantaneously imparted to the inflated air cushion bag at the time of collision of the automotive vehicles, it is subjected to deformation with the consequence that the circular air outlet port per se is also deformed from circle to ellipse, and, at the same time, following this deformation of the air outlet port, the gas-permeable cloth is stretched by a large resistance caused by the outflowing air to unavoidably stretch the cloth in the direction of the long (or major) diameter of the above-mentioned elliptically deformed air outlet port, as the result of which the cover cloth is bursted out, or the peripheral edge portion thereof joined to the main body of the air cushion bag is broken to make it difficult to secure a stable air outlet performance. The tearing of the cloth becomes enhanced when knitted fabric having a certain specific directivity in its elongation is used as the gas-permeable cloth material, and the tensile force is applied to the direction where the cloth is rather difficult to stretch.